Compressed liquid gas filling system

ABSTRACT

Escaping gas from the 20 percent valve of a compressed liquid gas tank is fed through a metered opening into an expansion chamber. A temperature sensitive element located within the expansion chamber has a first ambient temperature position and a second lower temperature position. The escaping gas normally has the same temperature position. The escaping gas normally has the same temperature as the ambient; however, as the tank is filled beyond the 80 percent volume position, liquid gas is drawn into the expansion chamber where it immediately expands and vaporizes. The expanding process draws heat from the immediate surroundings, thereby lowering the temperature of the expansion chamber and the temperature sensitive element which assumes the second temperature position. Movement of the temperature sensitive element is coupled with a spring-loaded control valve feeding the compressed liquid gas tank, thereby closing the spring-loaded valve and stopping the filling process.

United States Patent Dalton May 28, 1974 COMPRESSED LIQUID GAS FILLINGPrimary Examiner-Leon G. Machlin SYSTEM [76] Inventor: Charles RobertDalton, 3107 57 ABSTRACT Newton, No. 40, Torrance, Calif. 90505 Escapinggas from the 20 percent valve of a compressed liquid gas tank is fedthrough a metered open- 122] Flled: 1972 ing into an expansion chamber.A temperature sensi- [21] 3 g tive element located within the expansionchamber has a first ambient temperature position and a second lowertemperature position. The escaping gas nor- [52] US. Cl 141/39, 62/49,73/298, n has the same temperature position The eseap 116/118 R, 137/101- ing gas normally has the same temperature as the am- [51] Int. Cl.Bg 5/00 hieht; however, as the tank is fill d beyond the [58] new ofSearch 141/192 cent volume position, liquid gas is drawn into the ex-141/45, Wino/ P; H6/DIG- 118 R; pansion chamber where it immediatelyexpands and 73/290 298; 251/66 67, 74; 137/59 vaporizes. The expandingprocess draws heat from the 207'5, 214 immediate surroundings, therebylowering the temperature of the expansion chamber and the temperature[56] References Cted sensitive element which assumes the second tempera-UNITED STATES PATENTS ture position. Movement of the temperaturesensitive 2,630,818 3/1953 McRae 251/66 x element is coupled with aSpring-loaded Control valve 2,850,257 9/1958 Smith et al 251/66 Xfeeding the compressed liquid gas tank, thereby clos- 3,293,390 12/1966Shaw 116/118 R ing the spring-loaded valve and stopping the filling3,550,603 12/1970 Schueler 251/74 X rocegg 3,606,980 9/1971 Simpson etal. 251/66 X 20 Claims, 9 Drawing Figures I8 20% I I4 vu or I 1' voporl6 1 I h ii-TE 1 1 10 E i (Prior Art) QATENTEDMMH m: 3,812,888

SHEET 10F 3 24 Fig. 5%; 40"

IL/ /V M. 77 ii? I "f."

PATENTED MY 28 9 3.812 8 8 8 SHEU 2 0F 3 100 Top View Fig. 5.

1 COMPRESSED LIQUID GAS FILLING SYSTEM This invention relates to amethod and means for automatically filling a compressed liquid gas fueltank to a predetermined volume.

Compressed liquid gas does not exist in nature in the liquid state butrather must be manufactured or compressed into a liquid. There arebasically three kinds of compressed gases in use today; and they includeliquid petroleum gas, commonly known as LPG, liquid natural gas,commonly known as LNG, and compressed natural gas, commonly known asCNG. All three gases are compressed and stored under pressure, however,only LPG and LNG are stored as a liquid under pressure. The compressednatural gas (CNG) is normally stored under at least 2,000 pounds persquare inch pressure and is always stored as a gas and never as aliquid.

The present invention is concerned primarily with the automatic handlingof compressed liquid gases of the LPG or LNG type. Reference tocompressed liquid gas is intended to include all compressed gases storedunder pressure as a liquid.

Propane is part of the LPG gas family and is also known as LP gas. Theinitials LPG refer to liquified petroleum gas which is produced as oneof the many byproducts of the refing of pretroleum. The LP gas isproduced by either stripping heavy products from natural gas or fromrefineries where crude oil is refined into gasoline, kerosene, dieselfuel and other petroleum products. The LP gas is a natural product ofthis refining process. Propane is part of the LP gas family which whichis also commonly known as butane, bottled gas or tank gas.

Propane is basically a colorless, odorless liquid that will remain in aliquid state as long as it is under pressure. For commercialapplications an odorant is normally added to the propane gas in order togive the user an indication of the presence of the gas. Propane boils(turns into a vapor) at minus 44C, and as the fuel temperature variesfrom minus 44C to plus 100C, the propane molecules become more volatileand hence boil more rapidly. This low boiling temperature of the propaneliquid gas and the high volatility of the propane molecules as thetemperature increases causes the liquid propane when released toatmosphere to vaporize instantly into a completely vaporized gas.

For combustion engine applications, the completely vaporized propane gaswhen entering the carburetor assures an even gas/air mixture to allcylinders thereby resulting in more complete combustion. As a result ofhaving a more efficient combustion there is less carbon deposits, longerspark plug life and less oil dilution associated with the internalcombustion engine.

Unfortunately, the low boiling point of the LP gas creates a problem inholding the liquid gas in the fuel tank associated with the uservehicle. Normally the LP gas fuel tank is designed and constructed tohold a volume of liquid gas at a pressure of approximately 350 poundsper square inch. In view of the low boiling point of the LP gas and thefact that the LP gas fuel tank holding the gas under pressure issubjected to external ambient temperatures that may exceed 100 F, it canbe appreciated that the propane molecules located within the fuel tankwill boil more rapidly as the temperature increases. thereby increasingthe internal pressure within the gas tank.

Conventional safeguards require that all LP fuel gas tanks be designedand constructed and tested to withstand at least 1,000 pounds of staticpressure which is approximately 3% to four times the relief valvesetting. ln addition, all LP gas tanks are required to have a pressureoverload control valve (POC) which is sometimes in combination with thefeed valve for automatically releasing excess pressure from within thegas tank. An additional safeguard is the requirement that LP fuel gastanks only be filled to percent of their volume capacity in order tothereby allow 20 percent of the volume of the gas tank for expansionpurposes as the external ambient temperature changes.

The so-called 20 percent valve is an external valve communicating insidethe LP gas fuel tank with a vapor liquid level tube that is inserted apredetermined distance into the gas tank to represent 20 percent of theinternal volume. The opening through the walls of the fuel tank isapproximately the size of a No. 54 drill to thereby ensure that in theevent of an accident that the only fuel that would escape to atmospherewould be through the small 54 drill-size opening. During the fillingoperation the 20 percent valve is opened, thereby allowing vapor withinthe gas tank to escape through the liquid level tube, indicating to theoperator that the liquid level tube is in the presence of vapor only.

Filling the LP gas tank with liquid gas raises the level of the liquidwithin the fuel tank until the liquid level reaches the liquid leveltube. At that point the internal pressure within the tank forces a smallportion of liquid LP gas up the liquid level tube and out the external20 percent valve. The LP gas in the liquid state when released toatmosphere pressures immediately vaporizes causing a squirting of gas inthe form of a heavy white fog indicating to the operator that the liquidlevel within the tank has reached the 80 percent portion. The operatorthen immediately shuts off the fuel pump, closes the 20 percent valveand closes the fill valve on the fuel hose of the LP fuel tank.

The present invention is concerned with giving the operator a visualindication that the fuel tank has reached the 80 percent level. Inaddition, there is disclosed an apparatus for automatically turning offthe fuel supply when the tank is filled to the 80 percent level withoutrequiring any attendance from the operator. In connection with theabove, there is disclosed apparatus for recycling the vented gas vaporsthat are normally released to atmosphere during the filling pro cess.

In the present invention there-is described an expansion chamber havinga metered input that is connected to a LP gas fuel tank through a vaporliquid level tube extending into the gas tank. The liquid level tubewill normally be inserted a distance into the volume of the gas tank torepresent 20 percent of the total volume of the tank and at the otherend will communicate with the expansion chamber through a meteredopening. Located within the expansion chamber is a temperature-sensitiveelement capable of generating an output in the presence of a change intemperature. The actual sensitive element may include a thermister,resistor, thermocouple or thermal pressure bulb-type actuator forgenerating an electrical or mechanical signal in the presence of achange in temperature or a bimetallic material for generating a physicalmovement in the presence of a change in temperature.

Y manner through the FCC valve. As the gas tank is filled, the vaporlocated within the tank is forced through the liquid level tube into theexpansion chamher and out the vent hole located within the chamber.There is however, no change of temperature associated with the vaporsince the vapor is already in a completely vaporized state, and thetemperature of the vapor within the tank or within the expansion chamberwill be the same, and hence there will be no effect of the vaporized gason the thermometal disk which will remain in the normal ambient firsttemperature positron.

As the liquid level rises beyond the 80 percent volume position, aportion of the LP liquid gas will be forced through the liquid leveltube, through the metering opening and into the expansion chamber. Theliquid gas upon entry into the expansion chamber will immediatelyvaporize thereby absorbing heat and in the process of expanding andvaporizing will remove heat from the surrounding expansion chamber.Lowering the temperature of the expansion chamber and the thermometaldisk causes the thermometal disk to assume the second cooler temperatureposition; and in so doing, the spring-biased actuating rod is moved intoa second position for either closing the fuel valve or for operating anindicator to show that the tank is full.

The vaporized gases located within the expansion chamber may be exposedto the atmosphere for normal venting as is presently done with theconventional percent valve. However, in the preferred embodiment thevent may be connected to the suction line associated with the fuel pumpfor recirculating the vapors within the system so as to preventpollution of the atmosphere by the vaporized gases.

In the preferred embodiment a spring-loaded fuel valve is usedinconnection with feeding liquid LP gas into the fuel tank. Theexpanding liquid gas is used to cool a bi-metal member for operating anormally closed fuel valve. The vaporizing of the liquid gas against thethermometal material cooperating with a spring-loaded fuel valve resultsin the closing of the spring-loaded fuel valve into the OFF positionwithout the need of an operator observing or not observing the statedconditions.

Further objects and advantages of the present invention will be mademore apparent by referring now to the accompanying drawings wherein:

FIG. 1 is a block diagram of a conventional system for fillingcompressed liquid gas fuel tanks;

FIG. 2 is a sectional diagram of an expansion chamber illustrating athermometal disk in the ambient or first temperature position;

FIG. 3 illustrates an expansion chamber having a thermometal disk in acool or second temperature position;

FIG. 4 illustrates a block diagram of a complete system for fillingliquid gas fuel tanks according to the teachings of the presentinvention in which normally vented vapors are recirculated within thesystem;

FIG. 5 illustrates a second embodiment for recirculating normally ventedvapors within the system;

FIG. 6 illustrates the top view of a spring-loaded valve that isnormally biased in the OFF position;

FIG. 7 is a bottom view of the spring-loaded fuel valve illustrating thebiasing spring;

FIG. 8 is a schematic diagram illustrating how the spring-loaded fuelvalve is automatically shut off when the fuel tank approaches percent ofthe total volume; and

FIG. 9 is a block diagram illustrating how the expansion chamber andplunger may be used to automatically operate a spring-loaded fuel valve.

Referring now to FIG. I, there is shown a block diagram illustrating theprior art techniques for filling a compressed liquid gas fuel tank 10.Located on one side of the fuel tank 10 and preferably on the uppermostside is a liquid fill valve 12 and together with a 20 percent valve 14.A liquid level tube 16 projects within the fuel tank 10 a distance equalto 20 percent of the total volume of the tank. The upper end of theliquid level tube 16 is connected to the controllable 20 percent valve14.

The compressed liquid gas supply is normally maintained at servicestations in substantially large fuel tanks 18 under pressure. A fuelpump 20 is used to connect the output from the fuel tank 18 into theliquid fill valve 12 associated with the LP fuel tank 10.

In normal filling operation the connection is made as illustrated inFIG. 1 with the liquid fill valve 12 opened and the 20 percent valve 14opened. The pump 20 forces liquid gas under pressure from tank 18 intotank 10. As the liquid level within the tank 10 rises beyond the 80percent level, a portion of the liquid will enter the liquid level tube16 and be forced out the 20 percent valve 14. The operator by necessitymust stand near the tank being filled in order to observe the whitefoamy material which indicates that liquid is being vaporized in theatmosphere as it emerges from the 20 percent valve 14. The operator thenstops the pump 20, closes the 20 percent valve 14 and the liquid fillvalve 12, and removes the coupling between the pump 20 and the valve 12.At this point the fuel tank 10 is now filled to within 80 percent of thevolume capacity leaving 20 percent of the volume for vapor expansion asthe ambient temperature changes.

From the foregoing description of the prior art techniques it can beappreciated that an operator must remain in close proximity to thefilling of. the tank in order to prevent overfilling. This requirementplaces a severe restriction on the commercial applicability and use ofcompressed liquid gas systems for automobiles and other masstransportation media. The present invention is considered abreak-through in that it is now possible to use automatic means forfilling the LP gas tank without requiring an operator to be in immediateattendance during the filling procedure. It is now possible for theoperator to service a plurality of different vehicles at the same timewith the same facility that a single operator now services a pluralityof vehicles at a conventional gasoline dispensing station.

Referring now to FIG. 2, there is shown an expansion chamber 22 formedwithin a block 24 and insert 26. Block 24 is shown mounted external to aLP fuel tank 28. However, the block may be formed as part of the fueltank as an integral part or external to the fuel tank as shown. A vaporliquid level tube 30 is inserted into the fuel tank a distanceequivalent to 20 percent of the volume and at the other end communicateswith a metering orifice 32 located in block 24 that communicates withthe expansion chamber 22. A controllable vent 34 communicates theinterior of the expansion chamber 22 to the outside atmosphere. Alocking screw 36 provides a means for either opening or closing the vent34.

Located within the expansion chamber 22 is a thermometal disk 38 locatedin a sealing relationship between block 24 and insert 26. An O-ring 40located within a channel in block 24 provides a seal for the thermometaldisk 38 which is illustrated in a first ambient temperature position.

Located on the other side of the disk 38 is a springbiased actuating rod42 having an enlarged head portion 44. The head portion 44 has a firstside 46 for con tacting the thermometal disk 38 and a substantiallysquare shoulder side 48 that is opposite the rounded side 46. Insert 26contains a cylindrical opening 50 for accepting the actuating rod 42 anda substantially larger cylindrical opening 52 for accepting a spring 54that is located within the cylindrical opening 52. Spring 54 continuallyurges the head portion 44 of the plunger 42 to continually contact thethermometal disk 38.

FIG. 2 illustrates a quiescent condition in a fuel tank where the liquidlevel is below the level of the liquid level tube 30. The vapor withinthe upper portion of the tank also enters the liquid level tube 30 andthe expansion chamber 22. However, this vapor is at ambient temperatureand will not affect the thermometal disk 38 which will remain in thenormal warm temperature position.

Referring now to FIG. 3, there is shown the same embodiment comprisingan expansion chamber 22 illustrated in connection with FIG. 2. In FIG.3, however, the fuel tank 28 is being filled with liquid gas and thecaptive screw 36 is opened thereby allowing the vent 34 to communicatethe interior of the expansion chamber 22 with the outside atmosphere.During the filling operation the vapor normally located in the upperportion of the tank 28 is forced through the liquid level tube 30,through the expansion chamber 22 and out the vent 34 to the atmosphere.The vapor being at ambient temperature will have no effect upon thethermometal disk 38.

However, once the liquid level reaches the lower tip of the liquid leveltube 30, liquid is forced through the liquid level tube and through themetered opening 32 which communicates the liquid level tube 30 with theinterior of the expansion chamber 22. The compressed liquid gas uponbeing forced through the orifice 32 into the expansion chamber 22immediately expands and vaporizes causing an immediate heat loss in theenvironment of the expansion chamber 22. The resultant lowering of thetemperature within the expansion chamber 22 cools the thermometal disk38 which now assumes a cooled second temperature position as indicated.Flexing of th thermometal disk 38 causes the indicating rod 42 to bepushed out of the confined insert 26, thereby causing the tip of theactuating rod to be used either as an actuating mechanism to bedescribed further or as an indicator to the operator that the gas tankis 80 percent full. The vaporized gas within the expansion chamber 22 isremoved by the vent 34 to the outside atmosphere.

The inventive concept is predicated on the proposition that the meteredliquid from the orifice 32 upon entering the expansion chamber 22 willimmediately vaporize and cool the thermometal disk 38 located within theexpansion chamber. Since the cooling process is based upon the transientcondition, it is recognized that should the operator not stop thefilling process that liquid gas from the tank 28 may fill the expansionchamber 22 and be emitted from the vent 34 as a liquid which would thenvaporize into the atmosphere and in this condition would not continue tocool the thermometal disk 38. In order to prevent the plunger 42 frombeing withdrawn it is suggested that the thermometal disk 38 have amechanically preferred cold position as shown in FIG. 3 that requiresthe manual resetting of the element 38 back to the warm position. Thiswould mean that after the thermometal disk 38 has been cooled andassumed the position shown in FIG. 3 that subsequent warming of thethermometal disk will not cause the disk to return to the warm positionas shown in FIG. 2 until the operator depressed the plunger 42, causingthe metal disk 38 to be mechanically replaced into the warm position.This fail-safe feature will ensure that once the actuating arm 42 isoperated that the operating arm will remain in the operated positionuntil manually reset by the operator.

Referring now to FIG. 4, there is shown a block diagram of a completefilling system utilizing the principle of the present invention andwhich illustrates how the venting gas from the expansion chamber may bewithdrawn into the system and prevented from being re leased to theatmosphere as a contaminating gas. A pump 40 having an inlet side 42 isconnected to a source of liquid gas 44. An output 46 from the pump 40 isconnected to a liquid fill valve 48 attached to a fuel tank 50. Anexpansion chamber 52 communicating with the interior of the tank 50 bymeans of a liquid level tube 54 has a vent opening 56 connected to thesuction side 58 of the pump 40.

During the filling operation the pump 40 supplies gas from the source 44through the liquid fill valve 48 into the interior of the tank 50.Escaping vapors from inside the tank are fed through the vapor liquidlevel tube 54 into the expansion chamber 52 and out the vent hole 56back into the suction side 58 of the pump 40, thereby effectivelyrecirculating all venting gases from inside the tank 50. The processwill continue until the liquid level rises and allows liquid to fill theliquid level tube 54 which liquid will be injected through the meteringorifice into the expansion chamber 52 and vaporized, thereby cooling thethermometal disk 62 and forcing the actuating rod 60 into an operatingcondition. The operator on seeing the actuating rod will stop thepumping operation of pump 40, close the FCC valve 48, and cap theventing tube 56 associated with the expansion chamber 52. It can beappreciated therefore that during the filling operating all gasesnormally vented through the expansion chamber 52 will be pulled backinto the pump 40 and recirculated until the tank 50 is filled therebyensuring that no gases will be released to the atmosphere during thefilling operation.

Referring now to FIG. 5, there is shown another embodiment forrecapturing the venting gases during the filling operation so as toprevent contamination of the atmosphere. In this embodiment the block 66and the insert 68 forming the expansion chamber 70 is made an integralpart of the tank shell 72. In all other respects the vapor liquid leveltube 74 communicating with the expansion chamber 70 and the thermometaldisk 76 located within the expansion chamber and the vent opening 78leads to the jet pump for evacuating gases from the expansion chamber52. Also located on the tank shell 72 is a liquid fill valve 80 having afitting 82 for accepting the nozzle from the pump 40 illustrated in FIG.4. The liquid fill valve 80 has a large internal diameter 84 and a smallprojection defining a reduced diameter 86 for effectively providing alow pressure area commonly known as a Venturi effect in the area 88between reduced diameter 86 and the enlarged diameter 84 of the liquidfill valve 80. The reduced diameter portion 88 is communicated by meansof an internal connection 90 with the vent opening 78 associated withthe expansion chamber 70.

In operation, liquid being inserted into the liquid fill valve 80through the fill fitting 82 will cause a low pressure area due to theVenturi effect that will effectively draw the accumulated gases withinthe expansion chamber 70 through the vent 78 and into the main stream offluid passing within the liquid fill valve 80. This process willcontinue as long as liquid fuel is inserted through the liquid fillvalve 80. In other words, all gases accumulating within the expansionchamber 70 will be continuously purged and recycled within the tank andprevented from being expelled into the atmosphere.

It will also be appreciated by those skilled in the art that the block66 and the insert 68 forming the expansion chamber 70 may be located aspart of the tank shell 72 as illustrated in FIGS. 2 and 3. In theexternal configuration the connection 90 between the vent 78 and the lowpressure area 88 associated with the liquid fill valve will be externalto the tank shell 72 rather than internal as illustrated. In any event,the operation will be the same which is to prevent external vapors fromescaping into the atmosphere.

Referring now to FIGS. 6, 7, 8 and 9, there is disclosed apparatus forutilizing the change of state of the escaping liquid fuel from a liquidstate to a gaseous state as the means for controlling a spring-loadedfuel valve 90 that is normally biased in the OFF position.

Referring now to FIGS. 6 and 7, there is shown a spring-loaded fuelvalve 90 that is biased by a spiraled spring 92 into the normally closedposition. The operating handle 94 controls the internal valve operatingmechanism and is attached on the top side as illustrated in F IG. 6 to acam 96 and on the bottom side to the spiraled spring 92. A stop 98located on the body of the valve 90 limits the movement of the cam 96 byabutting against a flat surface 100 located on the cam. A detent ornotch 102 is cut in the cam 96 approximately 90 from the flat surface100. The notch 102 is adapted to receive a locking member that will holdthe operating arm 94 in the open position. When the locking member isretracted from the notch 102, the spiral spring 92 is free to rotate theoperating arm 94 to the closed position with the cam surface 100abutting against the stop member 98.

Referring now to FIG. 8, there is shown a first embodiment forautomatically shutting off the fuel supply valve feeding the liquid fillvalve 80 on a fuel tank. There is illustrated an automatic shut-offvalve 90 similar to that described in connection with FIGS. 6 and 7.Located on one side of the valve by means of screws 104 is a bi-metallicstrip 106 that has a normally preferred warm position against the valvebody and a cool position that is away from the valve body. The free orcantilevered end 108 of the bi-metallic strip 106 is adapted to fit intothe notch 102 cut into the cam 96.

In the normal warm position, the bi-metallic strip 106 V is locatedclose to the valve body 90 so that tip 108 is located within the notch102 thereby holding the valve operating arm 94 in the open position.

The conventional 20 percent valve 110 located on the tank shell 112 isconnected by means of a flexible tube 114 to the valve body 90 where thefree end of the tube 116 faces the bimetallic 106 so that fumes from the20 percent valve 110 will completely envelop the bi-metallic strip 106.As mentioned previously in connection with the expansion chamberillustrated in FIGS. 2 and 3, the normal vapors escaping from the vaporliquid level tube 111 associated with the 20 percent valve 110 willconduct vapors that are at the ambient temperature. Since there is nochange of state of the vapors when exposed to the expansive atmosphere,there is therefore no change in the temperature of the vapors.

The change of temperature is associated only with the expansion of theliquid gas when it is conducted to either the expansion chamberassociated with FIGS. 2 and 3 or to the expansive atmosphere in whichthe bimetallic strip 106 is located as illustrated in FIG. 8. The liquidgas fed from the 20 percent valve 110 through the tube 114 will normallybe removed at the tip 116 as a liquid. As soon as the liquid hits theatmosphere it immediately expands and vaporizes thereby cooling theimmediate area which is the bi-metallic strip 106 causing the strip tobe cooled and thereby fold away from the main body of the valve 90.Movement of the bimetallic strip 106 will cause the tip 108 to bedisplaced from the detent 102 located in the cam 96. With the cam 96 nolonger held in a restraining position by the tip 108, the operating arm94 is free to move into the normally closed position by the action ofthe biased spring 92. It can be appreciated therefore that as soon asthe liquid level within the tank sheet 112 approaches the 20 percentvolume area that the vaporizing liquid from the tip 116 will cool thebi-metallic strip 106, thereby immediately closing the valve 90 in asafe and automatic fashion.

Referring now to FIG. 9, there is shown a second embodiment forautomatically controlling an automatic shut-off valve in response to theliquid level approaching more than 80 percent of the total volume of thefuel tank. The system described in connection with FIG. 9 contemplatesthe use of an expansion chamber 120 formed from a block 122 and aninsert 124 in a similar fashion as described in connection with FIGS. 2and 3. The essential difference is that the thermometal 126 has anormally warm ambient position so as to force the actuating rod 128against the action of a spring 130 into a normally extended position asshown. In all other respects the system is similar to that previouslydescribed with the liquid level tube 132 extending through the tankshell 134 a distance equal to approximately 20 percent of the internalvolume of the tank 134. A vent 136 is connected to the suction side of apump 138 for removing all vapors from the interior of the expansionchamber 120. One end of the pump 138 is connected to a tank 140 ofcompressed liquid gas which is pumped through a spring biased valve 142of the type described and illustrated in connection with FIGS. 6 and 7.

The normally extended plunger 128 is adapted to fit within the detent102 of the cam 96 as illustrated in FIG. 6 thereby holding the operatingarm 144 in the open position against the operation of the coil spring 92as illustrated in FIG. 7. The discharge end of the automatic shut-offvalve 142 is connected to the liquid fill valve 146 located on the tank134.

In the normal filling operation, the liquid fill valve 146 is open andthe operating arm 144 of the automatic shut-off valve 142 is moved tothe open position with the normally extended plunger 128 inserted intothe detent 102, located on the cam 96. The pump 138 is turned ON andcompressed liquid from the storage tank 140 is forced into the tank 134.As the liquid level of fiuid rises and contacts the bottom portion ofthe liquid level tube 132, a metered amount ofliquid is forced from theliquid level tube 132 into the expansion chamber 120 where it isvaporized and cools the thermometal disk 126, causing the disk 126 tomove into a lower position in view of the cooling action caused by thevaporizing liquid within the chamber 120. The thermometal disk 126 underthe urging of spring 130 will cause the plunger 128 to be retracted adistance sufficient to allow the end portion of the plunger to pull freeof the detent 120 in the cam 96. With the cam no longer restrained bythe extended plunger 128 the operating handle 144 is now free to moveinto the OFF position under the urgings of the coiled spring 92. Oncethe automatic shut-off valve 142 has operated, all fuel from the storagetank 140 is prevented from entering the tank 134. The attending operatorneed only stop the pump 138 and close the liquid fill valve 146, removethe necessary lines, and cap the vent with a suitable cover of the typeshown in FIGS. 2 and 3. Due to the fail-safe feature of thespring-biased valve 90, there is no danger if the expansion chamber 120floods, since the valve would already have tripped The system describedin connection with FIG. 9 has an inherent advantage over the automaticsystem described in connection with FIG. 8 since the vapor fumes fromeither the 20 percent valve or from the vent associated with theexpansion chamber is now recycled and kept in the system withoutcontaminating the atmosphere.

I claim:

1. A system for filling compressed liquid gas tanks under pressurecomprising:

an expansion chamber having a metered input adapted to be connected to acompressed liquid gas tank for receiving a selected portion of the totaltank contents,

a temperature-sensitive element located within said expansion chamberfor generating an output on the expansion of said liquid to a gas insaid chamber, and

a controllable vent communicating with said expansion chamber forremoving accumulated gas from said chamber.

2. A system according to claim 1 which includes a vapor liquid leveltube communicating said said expan- 65 sion chamber at one end andinserted a predetermined distance into the compressed liquid gas tankwhereby liquid gas in said tank at a predetermined level is fed intosaid expansion chamber where it expands and thereby cools saidtemperature sensitive element.

3. A system according to claim 2 in which said compressed liquid gastank has an upper portion and a 5 lower portion and said vapor liquidlevel tube is inserted a distance equal to approximately 20 percent ofthe volume of said tank whereby liquid gas filling more than 80 percentof the volume of said tank causes liquid to enter said tube and saidexpansion chamber.

4. A system according to claim 1 in which said temperature-sensitiveelement comprises a bi-metallic material having a preferred positionunder ambient temperature conditions and a second position under lessthan ambient temperature conditions.

5. A system according to claim 1 in which said temperature sensitiveelement comprises a flexible thermometal disk held in a sealingrelationship within said expansion chamber for defining a first portionof said chamber that is sealed from said compressed liquid gas tank.

6. A system according to claim 5 which includes a movable plungerlocated within said first portion of said chamber and is continuouslyurged against one side of said disk,

said plunger extending in said expansion chamber and moving as saidflexible thermometal disk moves.

7. A system according to claim 6 in which said movable plunger comprisesan elongated stem portion extending through said expansion chamber andan enlarged head portion, I

said head portion having a first side for contacting said disk and asecond square side defining a sealing shoulder whereby extreme movementof said plunger causes said sealing shoulder to cover and seal theopening in said expansion chamber filled by said elongated stem.

8. A system according to claim 6 which includes indicia means controlledby said movable plunger whereby filling the compressed liquid gas tankto the predetermined volume is automatically indicated.

9. A system according to claim 1 which includes a pumping meansconnected to said controllable vent in said expansion chamber forremoving accumulated gas from said chamber.

10. A system according to claim 1 which includes means for pumping saidaccumulated gas from said vent in said expansion chamber back into saidcompressed liquid gas tank.

11. An automatic system for filling compressed liquid gas tanks underpressure comprising:

a service valve continuously biased in the OFF position adapted to beconnected to a source of-compressed liquid gas,

a temperature-sensitive element open to the atmosphere having a firsttemperature position and a second temperature position coupled to saidservice valve for holding said valve open when in said first positionand allowing said valve to close when in said second position, and avapor liquid level tube adapted to be inserted a predetermined distanceinto a compressed liquid gas tank at one end and at the other endcommunicating with said temperature sensitive element for feeding saidliquid gas against said element. 12. A system according to claim 11 inwhich an external hose is connected at one end to a 20 percent valveassociated with a compressed liquid gas tank and at the other end isdirected against said temperature-sensitive element.

13. A system according to claim 11 which includes a spring attached tosaid valve for continually urging said valve into the OFF position.

14. A system according to claim 11 in which said valve includes a camhaving a detent position attached to said valve and in which saidtemperature-sensitive element includes a bimetallic spring adapted tofit into said detent for holding said valve open against the springaction when in said first temperature position.

15. An automatic system for filling compressed liquid gas tanks underpressure comprising:

a service valve continually biased in the OFF position adapted to beconnected to a source of compressed liquid gas,

an expansion chamber having a metered input adapted to be connected to acompressed liquid gas tank for receiving a selected portion of the totaltank contents,

a temperature-sensitive element having a first temperature position anda second temperature position located within said expansion chamber andcoupled with said service valve for holding said valve open when in saidfirst temperature position and allowing said valve to close when in saidsecond temperature position, and

a controllable vent communicating with said expansion chamber forremoving accumulated gas from said chamberi whereby liquid gas in saidtank at a predetermined level is fed into said expansion chamber whereit expands and thereby cools said temperature-sensitive element.

17. A system according to claim 15 in which said temperature-sensitiveelement comprises a flexible thermometal disk held in a sealingrelationship within said expansion chamber for defining a first portionof said chamber that is sealed from said compressed liquid gas tank.

18. A system according to claim 17 which includes a movable plungerlocated within said first portion of said chamber and is continuouslyurged against one side of said disk,

said plunger extending in said expansion chamber and moving as saidflexible thermometal disk moves.

19. A system according to claim 15 which includes a pumping meansconnected to said controllable vent in said expansion chamber forremoving accumulated gas from said chamber.

20. A system according to claim 15 which includes means for pumping saidaccumulated gas from said vent in said expansion chamber back into saidcompressed liquid gas tank.

1. A system for filling compressed liquid gas tanks under pressurecomprising: an expansion chamber having a metered input adapted to beconnected to a compressed liquid gas tank for receiving a selectedportion of the total tank contents, a temperature-sensitive elementlocated within said expansion chamber for generating an output on theexpansion of said liquid to a gas in said chamber, and a controllablevent communicating with said expansion chamber for removing accumulatedgas from said chamber.
 2. A system according to claim 1 which includes avapor liquid level tube communicating said said expansion chamber at oneend and inserted a predetermined distance into the compressed liquid gastank whereby liquid gas in said tank at a predetermined level is fedinto said expansion chamber where it expands and thereby cools saidtemperature sensitive element.
 3. A system according to claim 2 in whichsaid compressed liquid gas tank has an upper portion and a lower portionand said vapor liquid level tube is inserted a distance equal toapproximately 20 percent of the volume of said tank whereby liquid gasfilling more than 80 percent of the volume of said tank causes liquid toenter said tube and said expansion chamber.
 4. A system according toclaim 1 in which said temperature-sensitive element comprises abi-metallic material having a preferred position under ambienttemperature conditions and a second position under less than ambienttemperature conditions.
 5. A system according to claim 1 in which saidtemperature sensitive element comprises a flexible thermometal disk heldin a sealing relationship within said expansion chamber for defining afirst portion of said chamber that is sealed from said compressed liquidgas tank.
 6. A system according to claim 5 which includes a movableplunger located within said first portion of said chamber and iscontinuously urged against one side of said disk, said plunger extendingin said expansion chamber and moving as said flexible thermometal diskmoves.
 7. A system according to claim 6 in which said movable plungercomprises an elongated stem portion extending through said expansionchamber and an enlarged head portion, said head portion having a firstside for contacting said disk and a second square side defining asealing shoulder whereby extreme movement of said plunger causes saidsealing shoulder to cover and seal the opening in said expansion chamberfilled by said elongated stem.
 8. A system according to claim 6 whichincludes indicia means controlled by said movable plunger wherebyfilling the compressed liquid gas tank to the predetermined volume isautomatically indicated.
 9. A system according to claim 1 which includesa pumping means connected to said controllable vent in said expansionchamber for removing accumulated gas from said chamber.
 10. A systemaccording to claim 1 which includes means for pumping said accumulatedgas from said vent in said expansion chamber back into said compressedliquid gas tank.
 11. An automatic system for filling compressed liquidgas tanks under pressure comprising: a service valve continuously biasedin the OFF position adapted to be connected to a source of compressedliquid gas, a temperature-sensitive element open to the atmospherehaving a first temperature position and a second temperature positioncoupled to said service valve for holding said valve open when in saidfirst position and allowing said valve to close when in said secondposition, and a vapor liquid level tube adapted to be inserted apredetermined distance into a compressed liquid gas tank at one end andat the other end communicating with said temperature sensitive elementfor feeding said liquid gas against said element.
 12. A system accordingto claim 11 in which an external hose is connected at one end to a 20percent valve associated with a compressed liquid gas tank and at theother end is directed against said temperature-sensitive element.
 13. Asystem according to claim 11 which includes a spring attached to saidvalve for continually urging said valve into the OFF position.
 14. Asystem according to claim 11 in which said valve includes a cam having adetent position attached to said valve and in which saidtemperature-sensitive element includes a bimetallic spring adapted tofit into said detent for holding said valve open against the springaction when in said first temperature position.
 15. An automatic systemfor filling compressed liquid gas tanks under pressure comprising: aservice valve continually biased in the OFF position adapted to beconnected to a source of compressed liquid gas, an expansion chamberhaving a metered input adapted to be connected to a compressed liquidgas tank for receiving a selected portion of the total tank contents, atemperature-sensitive element having a first temperature position and asecond temperature position located within said expansion chamber andcoupled with said service valve for holding said valve open when in saidfirst temperature position and allowing said valve to close when in saidsecond temperature position, and a controllable vent communicating withsaid expansion chamber for removing accumulated gas from said chamber.16. A system according to claim 15 which includes a vapor liquid leveltube, communicating with said expansion chamber at one end and inserteda predetermined distance into the compressed liquid gas tank, wherebyliquid gas in said tank at a predetermined level is fed into saidexpansion chamber where it expands and thereby cools saidtemperature-sensitive element.
 17. A system according to claim 15 inwhich said temperature-sensitive element comprises a flexiblethermometal disk held in a sealing relationship within said expansionchamber for defining a first portion of said chamber that is sealed fromsaid compressed liquid gas tank.
 18. A system according to claim 17which includes a movable plunger located within said first portion ofsaid chamber and is continuously urged against one side of said disk,said plunger extending in said expansion chamber and moving as saidflexible thermometal disk moves.
 19. A system according to claim 15which includes a pumping means connected to said controllable vent insaid expansion chamber for removing accumulated gas from said chamber.20. A system according to claim 15 which includes means for pumping saidaccumulated gas from said vent in said expansion chamber back into saidcompressed liquid gas tank.